1. Field of the Invention
The present invention relates to a method of manufacturing a fluid path structure to be used for conveying liquid, which may typically be a fluid path structure to be used in an inkjet head.
2. Description of the Related Art
Structures having fluid paths for conveying fluid such as liquid or gas in the inside of the three-dimensional body thereof by covering a resin plate having grooves formed on the surface thereof by means of a flat resin plate bonded thereto are known. For example, a holder unit that is a component of a liquid ejection head such as a tank-mounted inkjet head is one of such structures.
Such a holder unit includes a resin-made holder and a fluid path forming member and is produced by welding them together at the opposite surfaces thereof. Grooves that become ink path and ribs to be welded that run along the grooves are arranged on the surface to be welded of the fluid path forming member. On the other hand, grooves are arranged at the positions opposite to the respective ribs on the surface to be welded of the holder. Ink paths are completed as the holder and the fluid path forming member are joined together typically by means of an ultrasonic welding method.
Generally, alignment means are arranged on a pair of resin members of the above-described type that are to be welded together in order to weld them properly. Japanese Patent Application Laid-Open No. 2007-007968 discloses an alignment structure for suitably aligning two members without interfering with the operation of welding the two members.
With an ultrasonic welding method, the resin members that have welding zones are brought into contact with each other and then fused at the welding zones and joined together by means of the frictional heat that is generated due to the vibrations and pressure applied to them. Particularly, in the case of welding a fluid path forming member to be used for conveying fluid, the member needs to be reliably fused and joined with the partner member at the welding zones thereof in order to achieve airtightness for the fluid paths.
Conventionally, a fluid path forming member to be used for an inkjet head having a holder unit is aligned in the above-described manner and welded to the partner member typically by ultrasonic welding to produce fluid paths in it. In such welding operations, the conventional welding technique has been acceptable even if the members to be welded contact with each other at areas other than the welding zones such as the alignment areas and/or one or more than one outer peripheral parts of the fluid path forming member.
However, if the number of color inks is increased and/or if larger fluid path forming members and/or more complicated ink paths are employed in the future, the vibration energy that is applied to the welding zones will be lost, if partly, at the contact area or areas while the welding operation is proceeding to consequently degrade the performance of the welding operation particularly at parts located near the contact area or areas, which results in liquid leakage.